1. Field of the Invention
The invention relates to circuits for controlling wiper motors.
2. Description of the Prior Art
It often occurs that in automotive wiper installations the output torque of the wiper motor is insufficient to move the wiper blade over a dry pane. The motor then blocks and is subject to damage from overheating. In order to protect such a motor against destruction, thermo-switches are connected into the operating circuit which periodically interrupt the circuit. The motor is then energized in a pulse mode, whereby the ratio of deenergized interval to pulse duration is large so that the motor is not overheated. The switching operation of such thermo-switches is affected by the outside temperature, so that under certain circumstances it is switched off prematurely. Moreover, it is difficult to realize a sufficient aforementioned ratio.